All previous posters on this subject have somehow missed the 500# gorilla in the room. Multiple branch circuits cannot be allowed to âÂÂshareâ a common neutral conductor run without increasing the current carrying capacity of that run (larger size, DO NOT DOUBLE RUN WIRE, gang breakers). In such application power lost to heat more than doubles for a doubling of current, following square law (I-squared-R), dangerously violates code and it will burn down. This is the very reasoning behind licensing of electricians; if you donâÂÂt understand this, do not perform wiring and do not shuffle the load centerâÂÂs runs. However, âÂÂbalanced neutral/phaseâ is valid for load runs and mandatory on the supply-side of the bus; and is taken advantage of, by discriminating technicians. Balanced is green, more efficient, reduces losses, brownout, etc. When a load is balanced between legs (2 just happens to work out to be single phase; and 3, three phase), it is NOT sharing a run, but current is mutually excluded from the common neutral run (i.e., current does not circulate to the neutral runâÂÂs lug) to the extent that each leg mirrors the other(s). Hexus, think exclusive OR (XOR, only analog). Each circuit when used alone has exclusive use of that run. Under no circumstances does current exceed the runâÂÂs rating, ANYWHERE. When the circuitâÂÂs legs have matched loads (in current mirror, reactances in quiescence), think about identical hot plates on each leg, then the neutral run to lug will be cold, out of circuit and may be snipped to no affect. The neutral run BETWEEN hot plates will carry just one circuitâÂÂs current for either/all leg(s) (in series for 2-leg circuit; 3-phase âÂÂmotorsâ have all neutrals removed--there is no need for them with no current to run). Instead of I-squared-R loss over MULTIPLE neutral runs to lug; the loss is over a short distance ONLY between hot plates. Circuit interrupters (breakers) are now required to be âÂÂgangedâ (hence branch circuit fuses are not allowed) in order to arrest all branch neutral current. Sleeping rooms (including family/den/living rooms) require a 'split circuit' AFCI. GFCI's will de-energize with PROTECTED neutrals in common.

first of all the nonsense that you are describing is in no way, shape or form a mwbc. you should probably review the definitions in the front of the code book as calling things by the wrong name could cause confusion. second, the "super neutrals" referred to in an earlier reply are for a completely different purpose. they are up sized to allow for the extra current generated by non linear loads, but are used on normal mwbc's. as i already stated, the strange conglomeration you are talking about doesn't qualify as a mwbc. now, with that said, what you are talking about doing IS allowed by the code, but only for outdoor lighting i believe. i want to say to check 225.7b (no code book handy, been out of work for a while now). if you have the handbook i believe there is even extra explanatory material on this topic. since this particular section of the code is the only section i can recall that specifically allows this wiring method, i ASSUME that means that it is the only situation where this is permitted. of course, i could be mistaken about that. what i don't understand though, is if you are such a big fan of mwbc's, why would you even want to do this? you would be completely negating any of the benefits associated with running mwbc's. you would eliminate the possibility of balancing neutral current (unless you added yet another hot leg off the other phase), and without the neutral being balanced it also would not help with voltage drop at all. long story short, even though it's feasible, you'd be much better off just running multiple mwbc's.

When we were looking for a house, here in the wild wild west of SoCal, there was one listing that just seemed too good to be true. It was a listing for two great little houses on the same property in a nice neighborhood. Live in one, rent one kind of deal. But the asking price was really, really low. Even below the frequent "I'll list it low to create a bidding war" that you see a lot of around here. My realtor did some digging and discovered the reason for the lowball asking price... The second house was completely unpermitted. I can't remember if the area was even zoned for multi family or not but someone built an entire second house on their property without getting any approval from anyone. And no one noticed! It seemed kind of crazy to me. We decided to pass on looking at that one.

A 1 1/2 story house up the street was sold sometime this summer and the new owner (a realtor who intends to flip this house) is putting on a 2nd story. All the neighborhood is up in arms as he's doing it very poorly. I think he didn't realize how much this would cost and is now cutting corners right and left. He's used Hardie Board in a heinous color for the 2nd story (1st story is brick). He has put in cheap vinyl windows. The previous owner had planted a small tree in front of the front chimney (hideous!) and he had it cut down - no, not to be able to do the construction but after it was done. She had also done some very outstanding layers landscaping in the front - really wonderful year 'round. All that was cut down - new owner said it isn't what "his buyers want". Well, who the heck are "his buyers''? It's what people expect in THIS neighborhood! He has turned a rather charming house into a 1970's cheap subdivision house in one of the most desirable neighborhoods in this town. Lord only knows what he's asking for this monstrosity. He has a sign out but it's not on the company's web site yet. No one objects to the 2nd story being added (but were surprised that the city allowed it - pretty strict these days with building permits). Good luck with your project! Please show us pictures!